Exercise treadmills are widely used for various purposes. Exercise treadmills are, for example, used for performing walking or running aerobic-type exercise while the user remains in a relatively stationary position, further, exercise treadmills are used for diagnostic and therapeutic purposes. For all of these purposes, the person on the exercise treadmill normally performs an exercise routine at a relatively steady and continuous level of physical activity. Examples of such treadmills are illustrated in U.S. Pat. Nos. 4,635,928, 4,659,074, 4,664,371, 4,334,676, 4,635,927, 4,643,418, 4,749,181, 4,614,337, 6,095,951 and 6,572,512.
Exercise treadmills typically have an endless running surface which is extended between and movable around two substantially parallel pulleys at each end of the treadmill. The running surface usually includes a belt made of a flexible material extended around the pulleys. The belt is normally driven by a motor rotating the front pulley. The speed of the motor is adjustable by the user through a set of user controls so that the level of exercise can be adjusted to simulate running or walking as desired.
The belt is typically supported by a deck or support surface beneath the upper surface of the belt. The deck is usually composed of wood or MDF, in order to provide the required support. In addition, a low-friction sheet or laminate is usually provided on the upper deck surface to reduce the friction between the deck and the belt. In most cases, decks are relatively rigid which can result in high impact loads on the user's feet, ankles and knees as the user's feet contact the belt and the deck. This is often perceived by users as being uncomfortable and further can result in unnecessary damage to joints as compared to running on a softer surface.
Because the typical treadmill has a very stiff, hard running surface and can become uncomfortable for extended periods of running, manufacturers have sought to make the running surface more resilient in an attempt to improve user comfort. U.S. Pat. Nos. 3,408,067, 4,350,336, 4,616,822, 4,844,449, 5,279,528, 5,441,468, 5,454,772 and 6,095,951 disclose examples of resilient deck supports on treadmills to reduce impact loads. While reducing impact loads, these approaches have certain disadvantages. In some cases due to long usage, the resilient material loses its resiliency over time and becomes less resilient. In other cases, where the resiliency or spring rate of the deck supports made of a resilient material is constant, the supports usually will not provide adequate support and comfort for users having different weights and running styles. Another approach using resilient supports having a variable spring rate, such as shown in U.S. Pat. No. 6,095,951 do not allow the user to adjust the deck to achieve an individual comfort level. By the same token where the location of resilient support members can be changed, as described in U.S. Pat. No. 4,350,336, the resiliency of the deck is uneven along its longitudinal surface.
Accordingly, the invention provides a deck support that supports a deck of a human operable exercise treadmill that includes at least one resilient member configured generally as an arched leaf spring secured between the deck and the treadmill frame. The invention can also include a second such leaf spring spaced laterally from the first leaf spring or can include two sets of such leaf springs spaced longitudinally along the length of the deck.
In one embodiment of the invention, an adjustment linkage is coupled to at least one of the leaf springs and is operable to manipulate a first radius of the leaf spring(s) to vary the spring rate of the leaf spring(s). The adjustment linkage can similarly be operable to manipulate the radius of other leaf springs to vary the spring rates of these leaf springs as well. Specifically, the adjustment linkage can be operable to increase at least one of the leaf spring radii to decrease the spring rates and operable to decrease the radii to increase the spring rate.
In one embodiment of the invention, the adjustment linkage includes a first pivot that is pivotally supported on the treadmill frame and is coupled to a first leaf spring. A first lever is coupled to the first pivot, induces rotation of the first pivot in a direction to increase the first radius and induces rotation of the first pivot in another direction to decrease the first radius. The adjustment linkage can further include a second pivot that is pivotally supported on the treadmill frame and is coupled to a second leaf spring. A second lever is coupled to the second pivot, induces rotation of the second pivot in a direction to increase the second radius and induces rotation of the second pivot in a second direction to decrease the second radius.
In another embodiment, the deck support further includes a locking mechanism that is coupled to the adjustment linkage. The locking mechanism maintains the first and second radii at first and second desired settings, respectively.
In a further embodiment, the deck support additionally includes a third leaf spring having a third surface upon which the forward portion of the deck rests. The adjustment linkage is also coupled to the third leaf spring and is operable to manipulate the radius of the leaf spring so as to vary the spring rates of the leaf springs. If a fourth leaf spring is present, the adjustment linkage can similarly be connected to it as well.
In yet another embodiment, the adjustment linkage includes a first pivot that is pivotally supported on the treadmill and coupled to the first leaf spring and a second pivot that is pivotally supported on the treadmill and coupled to the third leaf spring. A lever is then coupled to the first and second pivots to induce rotation of the first and second pivots in a direction to increase the leaf spring radii and similarly to induce rotation of the first and second pivots in the other direction to decrease the radii.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.